1. Field of the Invention
This invention relates to an apparatus for attaching a pad eye to a surface and more particularly to an apparatus for attaching an explosive pad eye to an underwater surface.
2. Description of the Prior Art
In salvaging sunken ships, it is necessary to connect cables to the hull of the ship in some fashion so that the cables may be used to lift the ship. One simple way to accomplish this is to attach to the hull of the ship a pad eye, that is, a device having a base and some form of an opening in an upstanding member attached to the base. After the base portion is attached to appropriate places on the hull, the cables are placed through the openings and used to raise the sunken ship.
Various methods have been tried to attach the base to the hull. In the case of steel ships, the attachment is difficult since traditional nail or screw techniques do not work. Instead, the traditional approaches include welding or driving explosive rivets into the hull. Unfortunately, these techniques are not completely satisfactory.
In U.S. Pat. No. 4,051,797, a system for salvaging ships is shown which utilizes explosive rivets or bolts to attach cables to the ship. The rivets or bolts are explosively driven into the steel hull. However, the holding power and certainty of such devices is less than that of welded devices.
Another salvaging method uses electrical welding to attach a large plate to the hull of a sunken ship, as shown in U.S. Pat. No. 2,374,134. While this method utilizes the preferred method of attachment, namely welding, it is bulky and difficult to use. The device must be suspended from the salvaging ship and lengthy electrical cabling is used.
Another method utilizes a Thermit reaction to weld a plate to an underwater surface (U.S. Pat. Nos. 3,871,315 and 4,062,485). However, this method is also not entirely satisfactory.